Formation of the four different medetomidine glucuronides by recombinant UGTs Most human UGTs were assayed, and those exhibiting activity above the quantification limit (0.2 pmol/min/mg protein) are shown in the table. The other tested UGTs were 1A1, 1A5, 1A6–1A10, 2B4, 2B11, 2B15, 2B17, and 2B28. The substrate concentration in the assays, either dex- or levomedetomidine, was 0.5 mM, the protein concentration was 2.4 to 3.5 mg/ml, and the reaction time was 120 min. Activities were measured in duplicate (<15% difference), and mean data are presented.
Relative Expression Levela | Dexmedetomidine | Levomedetomidine | ||||||
|---|---|---|---|---|---|---|---|---|
| DG1 | DG2 | LG1 | LG2 | |||||
| Normalized a activity (pmol/min/mg) | ||||||||
| UGT1A3 | 13 | 0.33 | 0.51 | 0.34 | 0.07 | |||
| UGT1A4 | 1.00 | 68 | 11 | 10 | 5.4 | |||
| UGT2B7 | 1.5 | N.D.b | 0.76 | N.D.b | 0.29 | |||
| UGT2B10 | 0.13 | 8.6 | 6.2 | 106 | N.D.b | |||
↵ a The relative expression level of each UGT was determined by immunodetection (for further details, see Materials and Methods), and the normalized activities were calculated by dividing the measured rate by the relative expression level
↵ b N.D., activity below quantification limit (0.2 pmol/min/mg protein)